An experimental documentation of a hypersonic shock-wave turbulent boundary layer interaction flow: With and without separation

An experiment, thoroughly documenting the flow field resulting from the interaction of a shock wave with a nonadiabatic hypersonic turbulent boundary layer, is described. Detailed mean flow and surface data are presented for two shock strengths resulting in attached and separated flows, respectively. The surface measurements include continuous pressure, shear and heat-flux distributions upstream, in, and downstream of the interaction regions. At closely spaced intervals along the surface, boundary-layer profiles of static and pitot pressure and total temperature were obtained from which velocity, density and static temperature profiles were derived. The data are presented in both graphical and tabular form. These data are of sufficient detail to validate advanced computer codes and their associated turbulence models

Combining Implicit Function Learning and Parametric Models for {3D} Human Reconstruction

Implicit functions represented as deep learning approximations are powerful for reconstructing 3D surfaces. However, they can only produce static surfaces that are not controllable, which provides limited ability to modify the resulting model by editing its pose or shape parameters. Nevertheless, such features are essential in building flexible models for both computer graphics and computer vision. In this work, we present methodology that combines detail-rich implicit functions and parametric representations in order to reconstruct 3D models of people that remain controllable and accurate even in the presence of clothing. Given sparse 3D point clouds sampled on the surface of a dressed person, we use an Implicit Part Network (IP-Net)to jointly predict the outer 3D surface of the dressed person, the and inner body surface, and the semantic correspondences to a parametric body model. We subsequently use correspondences to fit the body model to our inner surface and then non-rigidly deform it (under a parametric body + displacement model) to the outer surface in order to capture garment, face and hair detail. In quantitative and qualitative experiments with both full body data and hand scans we show that the proposed methodology generalizes, and is effective even given incomplete point clouds collected from single-view depth images. Our models and code can be downloaded from http://virtualhumans.mpi-inf.mpg.de/ipnet

A Statistical Model for Synthesis of Detailed Facial Geometry

Detailed surface geometry contributes greatly to the visual realism of 3D face models. However, acquiring high-resolution face geometry is often tedious and expensive. Consequently, most face models used in games, virtual reality, or computer vision look unrealistically smooth. In this paper, we introduce a new statistical technique for the analysis and synthesis of small three-dimensional facial features, such as wrinkles and pores. We acquire high-resolution face geometry for people across a wide range of ages, genders, and races. For each scan, we separate the skin surface details from a smooth base mesh using displaced subdivision surfaces. Then, we analyze the resulting displacement maps using the texture analysis/synthesis framework of Heeger and Bergen, adapted to capture statistics that vary spatially across a face. Finally, we use the extracted statistics to synthesize plausible detail on face meshes of arbitrary subjects. We demonstrate the effectiveness of this method in several applications, including analysis of facial texture in subjects with different ages and genders, interpolation between high-resolution face scans, adding detail to low-resolution face scans, and adjusting the apparent age of faces. In all cases, we are able to re-produce fine geometric details consistent with those observed in high resolution scans.Engineering and Applied Science

Validation of a model for thermal emission

An introduction to the more general aspects of thermal models is followed by a brief outline of the construction and range of possible applications of the computer models-developed at the University of Durham. The physical basis behind one of these models, which predicts temperatures both at the surface and within a one-dimensional non-vegetated object, is considered in some detail, and the construction' of the model is outlined. The sensitivity of the temperature predictions to changes in the values of .the input parameters required by the model are also discussed. Equipment was designed specifically to collect sufficient ground truth data to enable the validation of the model, and there is a complete description of the construction and operation of the apparatus. The subsequent interpretation of the data using the computer is also described. The validation of the model was carried out for two roads with concrete and asphalt surfaces, and consisted of a comparison between surface temperatures predicted by the model and those measured by a radiometer. The results of the comparison are discussed in some detail. The suitability of the model to predict temperature contrasts between two different surfaces was also investigated using the’ validation data. The model was next applied to the more complex problem of simulating the thermal behaviour of a south facing vertical sandstone wall. A comparison between the predictions of the model and data measured by a radiometer is given, and the problems that this type of simulation entails are discussed. A summary is given of the work carried out with the model, and suggestions are made for improvements to the model. Finally, the development of future types of model is considered

A comparison of semiglobal and local dense matching algorithms for surface reconstruction

Encouraged by the growing interest in automatic 3D image-based reconstruction, the development and improvement of robust stereo matching techniques is one of the most investigated research topic of the last years in photogrammetry and computer vision. The paper is focused on the comparison of some stereo matching algorithms (local and global) which are very popular both in photogrammetry and computer vision. In particular, the Semi-Global Matching (SGM), which realizes a pixel-wise matching and relies on the application of consistency constraints during the matching cost aggregation, will be discussed. The results of some tests performed on real and simulated stereo image datasets, evaluating in particular the accuracy of the obtained digital surface models, will be presented. Several algorithms and different implementation are considered in the comparison, using freeware software codes like MICMAC and OpenCV, commercial software (e.g. Agisoft PhotoScan) and proprietary codes implementing Least Square e Semi-Global Matching algorithms. The comparisons will also consider the completeness and the level of detail within fine structures, and the reliability and repeatability of the obtainable data

Doctor of Philosophy

dissertationThe explosion in computing power and its application to complex multiphysics problems has led to the emergence of computer simulation as a new way of extending the inductive methods of science. Many fields, particularly combustion, have been greatly changed by the ability of simulation to explore in great detail the implications of theories. But problems have also arisen; a philosophical foundation for establishing belief in simulation predictions, particularly important for complex multiphysics systems where experimental data are sparse, is sorely lacking. Toward the end of establishing such a foundation, a comprehensive philosophical approach to model validation, called instrumentalism, is proposed. A framework for verification and validation/uncertainty quantification (V&V/UQ) of codes is presented in detail, and is applied to a novel entrained flow coal gasification model implemented in the massively parallel simulation tool Arches. The V&V/UQ process begins at the mathematical model. The novel coal gasification model, which utilizes the direct quadrature method of moments (DQMOM) for the solid phase and large eddy simulation (LES) for the gas phase and accounts for coupling between the gas and solid phases, is described in detail. A verification methodology is presented in the larger context of validation and uncertainty quantification, and applied to the Arches coal gasification model. A six-step validation framework is adopted from the literature and applied to the validation of the Arches gasification model. One important aspect of this framework is model reduction, creating surrogate models for complex and expensive multiphysics simulators. A procedure for constructing surrogate response surface models is applied to the Arches gasification model, with several statistical analysis techniques used to determine the goodness of fit of the coal gasification response surface. This response surface is then analyzed using two methods: the Data Collaboration methodology, an approach from the literature; and a Monte Carlo analysis of the response surface. These analyses elucidate regions of parameter space where the simulation tool makes valid predictions. The Monte Carlo analysis also yields probabilities of simulation validity, given input parameter values. These probabilities are used to construct a prediction interval, which can then be used to compute the probability of a consistent simulation prediction

Surface Heterogeneity Affects Adsorption Selectivity for CO2 Over CH4 in Bare Mesostructured Silica with 2D Hexagonal Symmetry and Different Pore Size

Mesoporous silica-based materials are used as sorbents and supports in many fields. The ordered pore architecture of MCM-41, and the absence of interconnections, make it suitable as a model system. The surface is natively functionalized by many silanol groups, endowing the material with a polar surface to directly interact with the target species or to mount additional functional groups. Either bare or functionalized, surface silanol arrangement is crucial to material performance. In the case of CO2 capture with amine-functionalized silica, silanol groups are responsible for fundamental H-bonds during chemisorption, but they also modulate the effect and weight of humidity on the material performance. In addition, the silanol groups can also tune the weight of physisorption over chemisorption. The relationship between these aspects and the textural features of mesostructured silica has not been addressed in detail. In this study, computer models are employed to investigate the adsorption capacity and selectivity of bare mesostructured silica with three different pore sizes. Results are rationalized in terms of silanol surface density and pore curvature. The importance of the energetic inequivalence between Q3 and Q2 sites on the silica surface is emphasized, as this causes adsorption behavior to deviate from ideality

Knowledge-based systems and geological survey

This personal and pragmatic review of the philosophy underpinning methods of geological surveying suggests that important influences of information technology have yet to make their impact. Early approaches took existing systems as metaphors, retaining the separation of maps, map explanations and information archives, organised around map sheets of fixed boundaries, scale and content. But system design should look ahead: a computer-based knowledge system for the same purpose can be built around hierarchies of spatial objects and their relationships, with maps as one means of visualisation, and information types linked as hypermedia and integrated in mark-up languages. The system framework and ontology, derived from the general geoscience model, could support consistent representation of the underlying concepts and maintain reference information on object classes and their behaviour. Models of processes and historical configurations could clarify the reasoning at any level of object detail and introduce new concepts such as complex systems. The up-to-date interpretation might centre on spatial models, constructed with explicit geological reasoning and evaluation of uncertainties. Assuming (at a future time) full computer support, the field survey results could be collected in real time as a multimedia stream, hyperlinked to and interacting with the other parts of the system as appropriate. Throughout, the knowledge is seen as human knowledge, with interactive computer support for recording and storing the information and processing it by such means as interpolating, correlating, browsing, selecting, retrieving, manipulating, calculating, analysing, generalising, filtering, visualising and delivering the results. Responsibilities may have to be reconsidered for various aspects of the system, such as: field surveying; spatial models and interpretation; geological processes, past configurations and reasoning; standard setting, system framework and ontology maintenance; training; storage, preservation, and dissemination of digital records

A blind accuracy assessment of computer-modeled forensic facial reconstruction using computed tomography data from live subjects.

A computer modeling system for facial reconstruction has been developed that employs a touch-based application to create anatomically accurate facial models focusing on skeletal detail. This article discusses the advantages and disadvantages of the system and illustrates its accuracy and reliability with a blind study using computed tomography (CT) data of living individuals. Three-dimensional models of the skulls of two white North American adults (one male, one female) were imported into the computer system. Facial reconstructions were produced by two practitioners following the Manchester method. Two posters were produced, each including a face pool of five surface model images and the facial reconstruction. The face pool related to the sex, age, and ethnic group of the target individual and included the surface model image of the target individual. Fifty-two volunteers were asked to choose the face from the face pool that most resembled each reconstruction. Both reconstructions received majority percentage hit rates that were at least 50% greater than any other face in the pool. The combined percentage hit rate was 50% above chance (70%). A quantitative comparison of the facial morphology between the facial reconstructions and the CT scan models of the subjects was carried out using Rapidform(™) 2004 PP2-RF4. The majority of the surfaces of the facial reconstructions showed less than 2.5 mm error and 90% of the male face and 75% of the female face showed less than 5 mm error. Many of the differences between the facial reconstructions and the facial scans were probably the result of positional effects caused during the CT scanning procedure, especially on the female subject who had a fatter face than the male subject. The areas of most facial reconstruction error were at the ears and nasal tip